When using imaging devices for diagnostic purposes, clinicians often are looking for very subtle image features that can indicate the presence of disease. It is well known that brighter displays provide clinicians with the ability to see more subtle features as compared to darker displays having the same physical contrast. It is for this reason that medical displays in particular are typically designed to be as bright as possible.
Of course, it is also well known that higher luminance results in higher heat levels which speeds up degradation and decreases efficiency. And increasing the current (drive level) sent through the display or the backlight of the display, increases the rate of degradation. This is particularly true of transmissive displays, e.g., LED, OLED, EL, or CCFL, which utilize backlights. A backlight that is driven to produce maximum luminance output all of the time will degrade much more quickly compared to the same backlight that is driven at a lower value. Moreover, it is preferable for any display to be consistent over time, i.e. display the same image at the beginning and at the end of its lifetime. If the luminance setting is near maximum, the output luminance of that display will gradually reduce over time (as will the detectability of subtle features).